The invention relates to an interferometer for optically measuring an object.
The typical design of an interferometer for optical measuring comprises a light source, a beam splitter, and a detector. Using the beam splitter a light beam from the light source is split into a working beam and a reference beam. The working beam impinges the object to be measured and is at least partially reflected by it. The (partially) reflected working beam reenters the beam path of the interferometer and is here interfered with the reference beam on the detector. The measuring signal of the detector is therefore an interference signal of interfering beams.
A motion of the object in reference to the interferometer influences the frequency of the returned working beam so that by an evaluation of the detector signal deductions can be made about the motion of the object and particularly the speed of motion can be determined. Such devices are also called “Laser-Doppler—Vibrometers”.
For the optic measuring of an object it is frequently necessary to measure several measuring points on the object. This is the case in motor vehicle technology, for example, in order to detect oscillations of an internal combustion engine. Here, it is necessary to measure the oscillations at several points of the motor housing or at the vehicle body, e.g., to determine not-reproducible transient motor vibrations.